In 2009, an estimated 219,000 cases of lung cancer were diagnosed in the US (See Reference 1) It is the leading cause of cancer deaths and ˜80% of patients with primary lung malignancy have non-small cell lung cancer (NSCLC). Brain metastasis (BM) can affect up to 25% of these patients during their lifetime (See Reference 2). BM cause significant neurologic, cognitive, and emotional difficulties (See Reference 3) and negatively impact survival (See Reference 4). Previous efforts to characterize patients that will develop BM have been disappointing. Currently, prophylactic cranial irradiation (PCI) is offered to all small cell lung cancer patients (but not to NSCLC patients) with early-stage disease that have responded to therapy or have stable disease after initial systemic treatment (See Reference 5). However, better selection of patients to offer PCI will spare those patients unlikely to develop BM from PCI-related side effects. Currently, there are no common practice measures to reduce the risk of BM in NSCLC. In locally-advanced stage III NSCLC, a clinical trial to determine the benefit of PCI accrued slowly and the study was terminated early, and is therefore, not statistically powered to meet the primary endpoint of improvement in survival (See Reference 6). Thus, there is a need for improvement in patient stratification. Molecular biomarkers could be of benefit to stratify these patients, but the ability to obtain adequate, quality tumor tissue in a standardized fashion for genomic profiling can be challenging and hence limiting. Recently, microRNAs (miRNAs) have been studied to characterize tumors (See Reference 7). miRNAs are small non-coding RNAs of 21-25 nucleotides that may act as molecular biomarkers. Due to their influence on cell physiology, alteration of miRNA regulation can be implicated in carcinogenesis and disease progression. In general, one miRNA appears to regulate several hundred genes, and as a result, miRNA profiling could serve as a better classifier than gene expression profiling (See Reference 8).